-=> Mike Ross said to Greg Mayman
 -=> about "BIKE LIGHT" on 09-24-03  19:05.....

 MR> Found something in the ARRL Handbook about adding a capacitor across a
 MR> load to get an impedance match. Turns out they call this arrangement
 MR> an L-Network. They list 2 kinds, the 1st where the load R is less than
 MR> the source Rin and the other where R is greater than Rin, which is my
 MR> case. 

Yes, I'm familiar with the network. But again it is intended to
operate at a single frequency.

 MR> C turns out to be 350uF but it exhibits an almost 5 db peak near
 MR> 300Hz.

Not much use unless you can maintain a steady speed on the bike.

  Also a very large current flows in and out of the capacitor
 MR> which I'm afraid may heat the windings by the same amount as the lamp
 MR> since after all it is a real maximum power transfer!

That probably doesn't matter all that much. Capacitors are
intended to pass alternating current. Large capacitors are
intended to pass large currents, unless they have a very low
voltage rating.

If you're worried select a cap like the ones used in crossover
networks of PA bins. They are made to operate at VERY heavy
current - tens of amps in many cases.

  i.e. the source
 MR> dissipates as much power as the load or 3 watts each for a total of 6
 MR> watts, makes sense...

 MR> That's definitely not what I was looking to do with the bike light. My
 MR> aim was to maximize power to the light while minimizing the power lost
 MR> in the dynamo windings. I guess I was wrong after all. I am really
 MR> just looking to minimize voltage loss in Rin.

And maximize the light output over a wide speed range.

Yes, I understand. There is no simple answer....

From Greg Mayman, in beautiful Adelaide, South Australia
   "Queen City of The South"    34:55 S  138:36 E

... Laugh, and the world laughs with you; snore, and you snore alone.
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